Preheat the oven to 375 degrees. Coat 6 cups of a muffin tin with cooking spray or line with paper liners.
Crack the eggs into a large bowl. Use a whisk to blend the eggs until smooth.
Add the spinach, bacon and cheese to the egg mixture and stir to combine.
Divide the egg mixture evenly among the muffin cups.
Bake for 15-18 minutes or until eggs are set.
Serve immediately or store in the refrigerator until ready to eat. Top with diced tomatoes and parsley if desired.
